Reinforcements for structural members have been manufactured using pultrusion processes. This process generally involves wetting fibers with resin and pulling them through a mold where the resin is cured as a result of heating the resin. The mold tends to create relatively smooth surfaces on the sides of the reinforcement although some recesses are often present. Exemplary pultrusion processes are disclosed, for example, in the following patents: U.S. Pat. No. 3,895,896 which issued to White et al. on Jul. 22, 1975; U.S. Pat. No. 5,286,320 which issued to McGrath et al. on Feb. 15, 1994; U.S. Pat. No. 5,374,385 which issued to Binse et al. on Dec. 20, 1994; U.S. Pat. No. 5,424,388 which issued to Chen et al. on Jun. 13, 1995; U.S. Pat. No. 5,556,496 which issued to Sumerak on Sep. 17, 1996; U.S. Pat. No. 5,741,384 which issued to Pfeiffer et al. on Apr. 21, 1998; and U.S. Pat. No. 5,783,013 which issued to Beckman et al. on Jul. 21, 1998.
Another type of pultrusion process has involved spreading resin on a film such as Mylar, adding fiber materials, and then adding a top cover film to form an envelope that essentially becomes a flexible mold. This sandwich is shaped by tension and mechanical forms and is then pulled through an oven to cure the sandwich in the form that is desired.
A third variation of pultrusion provides for the fibers to be placed under tension, saturated with photo-initiated resin, pulled through a series of sized dies to form the fibers into a round bundle, and then exposed to high intensity ultraviolet light where curing is initiated. A surface coating is then applied and cured to provide a desired resin rich surface. This process has been used in forming strengthening members of fiber optic cables. Exemplary variations of this process are disclosed in U.S. Pat. No. 4,861,621 which issued to Kanzaki on Aug. 29, 1989; and U.S. Pat. No. 5,700,417 which issued to Fernyhough et al. on Dec. 23, 1997.
A forth variation of pultrusion provides for the fibers to be placed under tension, saturated with thermo-reactive resin, pulled through a series of sized dies to form the fibers into a round bundle while exposed to elevated temperatures such as found in an oven. This process has been used in the making of fishing rods and also adapted for fibreoptic cable members.